JP2005155067A - Joint structure of pile head part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint structure of a double-pipe type pile head part, which can reduce material costs by keeping the wall thickness and length of an outer steel pipe small in dimension, and which enables reduction in construction cost and the shortening of a construction period by reducing the amount of excavated soil in installation. <P>SOLUTION: The conical outer steel pipe 3, where an anchor bar 5 is fixed on a large-diameter side, is arranged around the head part of a pile 1 which is installed in ground in such a manner that the large-diameter side is positioned on an upside; a solidification material 4 is infilled into a gap between the pipe 3 and the pile 1; and at least a large-diameter side end of the pipe 3 is embedded in an upper footing 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a joint structure of a pile head in which a pile such as a steel pipe pile, a concrete-filled steel pipe pile or a ready-made concrete pile and a concrete structure such as a footing or a foundation beam located on the pile are joined.

  For example, as shown in FIG. 11, a conventional pile head joint structure in which a pile and a concrete structure such as a footing or a foundation beam located on the pile are joined together is an interior of a pile 21 such as a steel pipe pile. A method in which the steel bar 22 is arranged so as to protrude above the steel pipe pile 21 and the concrete is placed and the pile head is joined to a concrete structure 23 such as a footing or a foundation beam (inner rod method), or As shown in FIG. 12, a method of fixing a plurality of fixing bars 24 extending upward to the upper end portion of the outer surface of the steel pipe pile 21 by welding, placing concrete, and joining the pile head to the concrete structure 23. (Beard muscle method) is known.

However, in the inner rod method (saddle reinforcing bar method), since the arrangement space of the reinforcing bars is narrowed, the reinforcing bars are overcrowded and inferior in workability. Moreover, since a reinforcing bar is arrange | positioned inside the steel pipe pile 21, the cross-sectional efficiency with respect to bending is bad, and the yield strength of a junction part is small.
On the other hand, in the beard bar method, the rebar is arranged outside the steel pipe pile 21 as compared with the inner rod method, so that the cross-sectional efficiency is improved. However, due to the recent increase in bearing capacity of piles, the design for large-scale earthquakes, and the accompanying increase in the strength of pile bodies (thickening of steel pipes, filling with concrete), overstressing can be avoided even with the beard bar method. However, there may be a problem in workability, or depending on conditions, it may not be possible to construct a joint structure that matches the strength of the pile body. In addition, when welding the beard muscle after the pile is built, the working posture is poor, and there remains a problem in ensuring the quality of the joint.

  To solve such a problem, as shown in FIG. 13, a cylindrical steel pipe (outer steel pipe) 26 is arranged outside the pile 25, and a reinforcing bar 27 is installed between the pile 25 and the outer steel pipe 26. In addition, a method for joining the pile 25 and the concrete structure 29 in which the concrete 28 is filled in the gap is described (for example, see Patent Document 1). According to this double pipe method, since the reinforcing bar 27 is arranged outside the pile 25, the cross-sectional efficiency is improved.

Japanese Patent Laid-Open No. 11-13139

However, in the method shown in FIG. 13, the force between the concrete structure such as footing and foundation beam and the pile is transmitted through the outer steel pipe and the concrete filled in the gap with respect to the horizontal force at the time of the earthquake. Therefore, it is necessary to make the outer steel pipe and concrete have sufficient strength to withstand it.
Specifically, as shown in the figure, support pressures R1 and R2 from the filled concrete 28 act on the outer steel pipe 26 at the time of an earthquake, and thereby a horizontal force is exchanged with the pile 25. At this time, the outer steel pipe 26 is subjected to a cross-sectional force such as a shearing force, a bending moment or an oblique tensile force, and the outer steel pipe 26 needs to be thick enough to withstand this.
In addition, in order for the filled concrete 28 to stably exert a load transmission function by the support pressures R1 and R2, the outer steel pipe 26 has a difference between the pipe diameter D1 of the outer steel pipe 26 and the pile diameter D2 of the pile 25. It is necessary to ensure a sufficient length L (length excluding the embedding length in the concrete structure 29 from the entire length of the outer steel pipe 26). Further, the outer steel pipe 26 needs to have a wall thickness that can exert a sufficient restraining force to prevent a decrease in the proof stress of the filled concrete 28 due to the bearing pressure and split fracture when the bearing pressures R1 and R2 are applied.
Further, the tensile force T1 or the pushing force T2 acts on the reinforcing bar 27 by the bending moment M near the pile head. Further, when a pulling force N is applied to the pile 25 due to the locking of the structure, a tensile force T0 is also applied. Since it is necessary to surely transmit the force between the piles 25 without pulling out the reinforcing bars 27 against these forces, the length L of the outer steel pipe 26, that is, the adhesion length is considerably long, or at least It is necessary to provide a protrusion for adhesion in a corresponding section of the outer surface of the pile 25.

  Considering the above, the outer steel pipe 26 is a steel pipe having a considerably large thickness and a length L that is at least about 1.5 to 2.0 times the pile diameter D2 in order to ensure sufficient yield strength. This is desirable and results in a significant increase in material costs. In addition, since the outer steel pipe 26 is usually installed after pile construction, if the length L is large, the amount of excavation of the ground near the pile head at the time of installation increases, and in some cases it is necessary to bench cut or depending on the case. The construction cost and construction period will increase.

  The present invention was made in view of such circumstances, and in the joint structure of the pile head of the double pipe method, while suppressing the wall thickness and length of the outer steel pipe to reduce the material cost, It aims at providing the joint structure of the pile head which can aim at reduction of construction cost and shortening of a construction period by reducing the amount of excavated soil at the time of installation.

  In order to solve the above-described problem, the pile head joint structure according to claim 1 is configured such that a conical outer steel pipe having a fixing rod fixed on the large diameter side is installed in the ground with the large diameter side facing upward. A concrete structure which is disposed around the head of the pile and the solid steel is filled in the gap between the outer steel pipe and the pile, and at least the end portion on the large diameter side of the conical outer steel pipe is the upper part It is embedded in.

Here, the conical shape means having a tapered cross section.
The shape (length, outer diameter on the large diameter side) and wall thickness of the conical outer steel pipe may be structurally designed so that the required yield strength can be obtained according to the conditions of the pile and the generated bending moment. Regarding the length of the conical outer steel pipe, for example, the length excluding the embedding length in the upper concrete structure from the entire length of the conical outer steel pipe is about 0.5 to 1.5 times the outer diameter of the pile. Can be set to Moreover, about the outer diameter of the large diameter side of a conical outer steel pipe, it can set so that it may become about 1.5 to 2.0 times the outer diameter of a pile, for example.
As the pile, for example, a steel pipe pile, a concrete-filled steel pipe pile, a steel pipe pile in which concrete is packed in the vicinity of the pile head, a ready-made concrete pile, or the like can be used. The ready-made concrete piles include, for example, PHC (high-strength prestressed concrete) piles, PC (prestressed concrete) piles, RC (reinforced concrete) piles, and piles in which steel pipes are wound around these.
The solidifying material includes, for example, concrete or mortar.
The concrete structure includes, for example, a footing or a foundation beam.
For example, the fixing muscle can be fixed to the outer surface or the inner surface of the conical outer steel pipe. When fixing the fixing bars to the inner surface of the outer steel pipe, the entire length of the fixing bars is embedded in a solidified material such as concrete, so that corrosion can be prevented.

In the invention according to claim 1, since the conical outer steel pipe is used, a component force in the axial direction is generated on the conical surface with respect to the force transmitted from the pile through the solidified material, and the steel material A load support mechanism that can utilize the strength more effectively is formed. That is, a rational structure using the hypotenuse can be formed by making the outer steel pipe a cone instead of a cylinder. In addition, there is a force to press the solidified material interposed between the pile and the conical outer steel pipe in the direction of the upper concrete structure. As a result, a restraining effect is exerted on the solidified material, and the solidified material is resistant to bearing pressure and split fracture. And stable, and can exhibit greater strength than the case where the outer steel pipe is cylindrical. Furthermore, since the anchor bars are fixed to the conical outer steel pipe, the length of the outer steel pipe required for anchoring (the total length of the outer steel pipe is the same as in the case of the prior art in which the anchor bars are fixed in the solidified material by adhesion. It is not necessary to ensure the length excluding the length embedded in the upper concrete structure. Therefore, by using a conical outer steel pipe, the thickness and length of the outer steel pipe can be reduced, and the material cost can be reduced.
Moreover, since it is only necessary to excavate a region that rises obliquely from the outer surface position of the pile slightly below the lower end of the conical outer steel pipe to be installed, the amount of excavated soil is reduced compared to the case of a cylindrical outer steel pipe The construction cost can be reduced and the construction period can be shortened.

The joint structure of the pile head according to claim 2 is characterized in that, in the invention according to claim 1, a hardware is arranged between the outer steel pipe and the pile.
As the hardware, for example, a closed annular member or a member divided into a plurality in the circumferential direction can be used. Further, for example, those formed in a wedge shape can be used.

  In invention of Claim 2, since the metal object is arrange | positioned between a conical outer steel pipe and a pile, the dimensional error accompanying installation of an outer steel pipe and a pile is absorbed, and the small diameter side of a conical outer steel pipe It is possible to fit without gap between the end of the stake and the pile.

  The pile head joint structure according to claim 3 is the invention according to claim 1 or claim 2, wherein the outer steel pipe is placed on a placing plate fixed to the outer surface of the pile. It is characterized by that.

  In the invention described in claim 3, the solidified material can be filled only by placing the conical outer steel pipe on the head of the pile and placing it on the placing plate. In addition, it can be applied in a manner that easily copes with dimensional errors.

  The joint structure of the pile head according to claim 4 is the invention according to any one of claims 1 to 3, wherein each or any of the pile, the outer steel pipe, the hardware, and the mounting plate is It is characterized by being joined.

In the invention according to claim 4, it is possible to transmit an axial pushing force and a pulling force between the pile and the conical outer steel pipe, and also to transmit a force to the concrete structure via the fixing bars. It becomes possible.
In addition, if the conical outer steel pipe and the pile are joined directly or indirectly, when a bending moment acts on the pile, direct load transfer from the pile to the conical outer steel pipe increases, and the tensile side Since the load is transmitted directly from the entire circumference of the pile including the pile to the conical outer steel pipe, the excellent structural characteristics of the conical outer steel pipe using the component force in the axial direction of the hypotenuse are utilized more effectively. can do.

  The pile head joint structure according to claim 5 is the invention according to any one of claims 1 to 4, wherein a cylindrical portion is formed at an upper end portion of the conical outer steel pipe, and the cylindrical portion is provided with the cylindrical portion. The fixing muscle is fixed.

  In the fifth aspect of the present invention, since the cylindrical portion is formed at the upper end portion of the conical outer steel pipe, the fixing muscle can be easily fixed and the bent portion of the fixing muscle can be eliminated. Furthermore, by burying this cylindrical part in the concrete structure, the embedded part becomes a vertical surface, and the structure of this part becomes a more stable and reliable structure.

  The pile head joint structure according to claim 6 is characterized in that, in the invention according to any one of claims 1 to 5, a bearing plate is fixed to an upper end portion of the pile.

  In the invention described in claim 6, since the bearing plate is fixed to the upper end portion of the pile, it is possible to transmit the axial force of pushing and pulling between the pile and the concrete structure. When a pulling force acts on the pile, the pulling force is transmitted to the concrete and the solidified material below the bearing plate. Furthermore, the pulling force can be transmitted from the solidified material to the concrete structure via the conical outer steel pipe and anchor bars, and by using the bearing plate and the conical outer steel pipe in combination, the pulling force is stable. It can be a structure. Moreover, the bearing plate can increase the fixing degree of the pile head when a bending moment is applied to the pile, and can increase the bending moment that can be borne by the pile without being transmitted to the conical outer steel pipe. At this time, axial support pressure is transmitted from the bearing plate to the solidified material on the tension side of the pile, but the restraining effect on the solidified material is exhibited between the conical outer steel pipes, and this causes bending of the pile head joint. Yield strength can be further increased.

  The pile head joint structure according to claim 7 is embedded in the concrete structure in an upper end portion of the pile and / or the bearing plate in the invention according to any one of claims 1 to 6. The fixing muscle is fixed.

  In the invention according to claim 7, since the fixing bars are also fixed to the upper end portion of the pile and / or the bearing plate, a part of the force transmitted from the pile to the concrete structure is passed through the fixing bars. Since it is transmitted directly, the force that must be transmitted from the pile to the concrete structure via the conical outer steel pipe and the anchoring bars of the conical outer steel pipe is reduced. For this reason, the required proof stress with respect to a conical outer steel pipe becomes small, and the thickness and length of a conical outer steel pipe can further be reduced. In addition, the pulling force generated by the axial pushing force or the locking of the structure during an earthquake should be transmitted directly from the pile to the concrete structure by the anchor bars fixed to the upper end of the pile and / or the bearing plate. Can do.

  The pile head joint structure according to claim 8 is the invention according to any one of claims 1 to 7, wherein the fixing bar provided in the outer steel pipe, the fixing bar provided in the pile. In addition, a fixing member is fixed to at least one upper end portion of the fixing muscle provided on the bearing plate.

  In the invention according to claim 8, since the fixing member is provided at the upper end portion of the fixing bar, the fixing length of the fixing bar in the concrete structure can be shortened. As a result, reinforcement in the concrete structure 2 can be facilitated, workability can be improved, or an increase in fixing length when a high-strength reinforcing bar is used can be suppressed.

  The pile head joint structure according to claim 9 is the invention according to any one of claims 1 to 8, wherein the pile has an outer surface facing the solidified material and / or an inner surface of the outer steel pipe. Is provided.

In the invention described in claim 9, the protrusion provided on the outer surface facing the solidified material of the pile increases the fixing degree of the pile head when a bending moment acts on the pile, and transmits it to the conical outer steel pipe. Without increasing the bending moment that can be borne by the pile. At this time, the axial support pressure is transmitted from the protrusion to the solidified material on the pulling side of the pile, but the constraining effect on the solidified material is exerted with the conical outer steel pipe, thereby the bending strength of the pile head joint Can be further enhanced.
Moreover, the protrusion provided on the inner surface of the conical outer steel pipe prevents the conical outer steel pipe and the solidified material from shifting, and constructs a more stable structure against the axial force of pushing and pulling.

As described above, according to the present invention, in the joint structure of double pipe type pile heads, the thickness and length of the outer steel pipe are kept small, thereby reducing the material cost and excavating at the time of installation. By reducing the amount of soil, the construction cost can be reduced and the construction period can be shortened.
In addition, construction is also a simple task of simply putting a conical outer steel pipe around the head of the pile at the site and filling a solidified material such as concrete between them, without requiring special skills, Easy to handle construction errors at the pile head level.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and the description thereof is omitted or simplified.

FIG. 1 is a longitudinal sectional view showing a pile head joint structure according to a first embodiment of the present invention.
In this pile head joint structure, the head of a pile 1 and a footing (concrete structure) 2 made of a concrete-filled steel pipe pile or a steel pipe pile filled with concrete in the vicinity of the pile head are joined.
That is, a conical outer steel pipe 3 is arranged around the head of the pile 1 installed in the ground with the large diameter side on the upper side and the upper end substantially coincident with the upper end of the pile 1. The inner diameter on the small diameter side of the outer steel pipe 3 is set to be substantially the same as the outer diameter of the pile 1, and there is almost no gap between the small diameter side of the outer steel pipe 3 and the pile 1. A gap between the conical outer steel pipe 3 and the pile 1 is filled with a solidifying material 4 such as concrete or mortar. A plurality of fixing bars 5 are fixed to the upper end portion of the outer surface of the conical outer steel pipe 3 by welding or the like so as to protrude, for example, at regular intervals in the circumferential direction and vertically upward. The upper ends of the fixing bars 5 and the conical outer steel pipe 3 are embedded in the footing 2. A plurality of fixing bars 6 are also fixed to the upper end portion of the outer surface of the pile 1 by welding or the like so as to protrude, for example, at regular intervals in the circumferential direction and vertically upward. These fixing muscles 6 are also embedded in the footing 2. On the other hand, an upper rebar 7 and a lower rebar 8 extending in the horizontal direction are embedded in the footing 2.
At the time of construction, as shown in FIG. 2, the fixing bar 5 is fixed in advance to the conical outer steel pipe 3, and the conical outer steel pipe 3 is connected from above the pile 1 to which the fixing bar 6 is fixed, There are a method of covering the head of the pile 1 and a method of fixing the fixing muscle 6 to the head of the pile 1 after covering the head of the pile 1 with the conical outer steel pipe 3.

  In this pile head joint structure, the fixing bar 5 fixed in the footing 2 is fixed to the large diameter side end of the conical outer steel pipe 3 having a diameter larger than that of the pile 1. The cross-sectional area when resisting the bending moment can be increased in the RC cross-section portion constituted by the concrete in 2 and the fixing reinforcement 5. For this reason, since the cross-sectional efficiency is improved and the bending strength is increased, a high-strength pile head joint structure can be configured without using an overcrowded bar arrangement. It should be noted that the strength of the joint structure of the pile heads can be further improved by increasing the material strength of the fixing bars 5 or increasing the strength of the concrete of the footing 2.

Further, in the joint structure of the pile heads, since the fixing muscle 6 is also fixed to the upper end portion of the pile 1, a part of the force transmitted from the pile 1 to the footing 2 is directly transmitted through the fixing muscle 6. As a result, the force that must be transmitted from the pile 1 to the footing 2 via the conical outer steel pipe 3 and the fixing bar 5 is reduced. As a result, the required yield strength for the conical outer steel pipe 3 is reduced, and the thickness and length of the conical outer steel pipe 3 can be further reduced.
Further, regarding the pulling force generated by the axial pushing force or the locking of the structure in the event of an earthquake, not only the fixing bar 5 fixed to the conical outer steel pipe 3 but also the fixing bar 6 fixed to the upper end portion of the pile 1. Can also be transmitted directly from the pile 1 to the footing 2.
Further, since the inner diameter of the conical outer steel pipe 3 on the small diameter side is substantially the same as the outer diameter of the pile 1, the solidified material 4 can be filled only by covering the head of the pile 1 with the conical outer steel pipe 3. it can.
Here, the example in which the fixing bar is fixed to the upper end portion of the pile has been described. However, when the bearing plate is fixed to the upper end portion of the pile as shown in FIG. 9, the fixing bar is fixed to the bearing plate. Even if it is, the same effect is acquired.

FIG. 3 is a conceptual diagram showing transmission of force when a bending moment acts on the pile head joint structure of FIG. 1. The effect of using the conical outer steel pipe 3 will be described in more detail with reference to FIG.
When a bending moment M acts on the pile 1, the load is transferred directly between the pile 1 on the side where the pile 1 pushes the conical outer steel pipe 3, and the space between the conical outer steel pipe 3 and the pile 1 is filled. The force is transmitted to the conical outer steel pipe 3 through the solidified material 4 thus formed. That is, it is transmitted to the conical outer steel pipe 3 by the supporting pressures R1 and R2 of the solidifying material 4. Further, the force transmitted to the conical outer steel pipe 3 is sheared or bent by the anchoring portion 5 fixed to the embedded portion of the conical outer steel pipe 3 in the footing 2 or the upper end of the conical outer steel pipe 3. Is transmitted into the footing 2.

  Thus, when not all of the bending moment M of the pile 1 is transmitted to the conical outer steel pipe 3, but a part is transmitted to the upper end of the pile 1, the embedded portion of the pile 1 in the footing 2 or the pile 1 is directly transmitted to the footing 2 as a shearing force or a bending moment by the fixing muscle 6 fixed to the upper end portion of 1.

In this pile head joint structure, a conical outer steel pipe 3 is used, so a component force Q in the axial direction is generated on the cone surface with respect to the force transmitted from the pile 1 through the solidified material 4. As a result, a load support mechanism that can utilize the strength of the steel more effectively is formed. That is, a rational structure using the hypotenuse can be formed by making the outer steel pipe a cone instead of a cylinder.
Further, by using the conical outer steel pipe 3, a force for pressing the solidified material 4 that is blocked and interposed between the pile 1 and the conical outer steel pipe 3 in the direction of the footing 2 is generated, thereby restricting the solidified material 4. Therefore, the solidified material 4 is stable against bearing pressure and split fracture, and can exhibit greater strength than the case where the outer steel pipe is cylindrical.

Further, since the fixing bar 5 is fixed to the conical outer steel pipe 3, as in the conventional technique of FIG. 13, the fixing bar 27 is fixed by adhesion in the solidified material (filled concrete 28). It is not necessary to secure the length L of the outer steel pipe 26 having a length necessary for fixing.
From the above, the thickness and length of the outer steel pipe 3 can be reduced by using the conical outer steel pipe 3.

  The shape (length, diameter on the large diameter side) and thickness of the conical outer steel pipe 3 may be structurally designed so that the required yield strength can be obtained according to the conditions of the pile 1 and the generated bending moment. As one guideline, the length L excluding the length embedded in the upper concrete structure (footing 2) from the entire length of the conical outer steel pipe 3 is 0.5 to 1.5 times the outer diameter of the pile 1 As long as the outer diameter of the conical outer steel pipe 3 on the large diameter side is about 1.5 to 2.0 times the outer diameter of the pile 1, a pile head joint structure having sufficient strength can be configured.

  4 and 5 are diagrams for explaining a region of the ground that needs excavation, and FIG. 4 relates to the pile head joint structure of FIG. 1 according to the present embodiment. Is a pile head joint structure as a conventional example using a cylindrical outer steel pipe 26 instead of the conical outer steel pipe 3. 4 and 5, the fixing bar is not fixed to the pile 1, and the fixing bar 5 is fixed to the upper end portion of the outer surface of the outer steel pipe 28 in FIG. 5. The effect of reducing the amount of excavated soil when the conical outer steel pipe 3 is used will be described with reference to these drawings.

In these figures, it is assumed that the ground is excavated at an angle of approximately 45 ° from the ground surface. In the case of FIG. 4 using the conical outer steel pipe 3, it is only necessary to excavate only the region A that rises at approximately 45 ° from the outer surface position of the pile 1 slightly below the lower end of the conical outer steel pipe 3 to be installed. . On the other hand, in the case of FIG. 5 using the cylindrical outer steel pipe 26, the cylinder has a depth to the position of the lower end of the outer steel pipe 26 to be installed and a width from the outer surface of the pile 1 to the outer surface of the outer steel pipe 26. It is necessary to excavate a region B that is a plus of the shape region and a region that rises at approximately 45 ° from the outer peripheral position of the lower end of the outer steel pipe 26. Thus, the amount of excavated soil can be reduced by using the conical outer steel pipe 3.
In FIG. 4, after excavation, when the conical outer steel pipes 3 are installed and voids remain outside the conical outer steel pipes 3, the excavated earth or sand is backfilled, or the conical outer steel pipes 3 and piles are removed. When the solidifying material 4 is filled in the gap between the first and second gaps, the solidifying material 4 may be filled in the gap at the same time.

FIG. 6 is a longitudinal sectional view showing a pile head joint structure according to the second embodiment of the present invention.
In this Embodiment, the edge part by the side of the small diameter of the conical outer steel pipe 3 is joined to the pile 1A which consists of a steel pipe pile by welding etc. In the case of joining by welding, welding is possible from the upper side to the lower side.

FIG. 7: is a longitudinal cross-sectional view which shows the joining structure of the pile head which concerns on the 3rd Embodiment of this invention.
In the present embodiment, a conical outer steel pipe 3A is used in which the inner diameter on the small diameter side is slightly larger than the outer diameter of the pile 1A, and this conical outer steel pipe 3A is formed around the head of the pile 1A. The large-diameter side is disposed on the upper side, and the upper end thereof is substantially aligned with the upper end of the pile 1A. Between the lower end portion of the conical outer steel pipe 3A and the pile 1A, an annular metal object (annular member) 11 having a triangular cross-sectional shape and a circular inner surface is fitted from above. And the conical outer steel pipe 3A, and the annular metal piece 11 and the pile 1A are joined by welding or the like. In the case of joining by welding, welding is performed downward from the upper side. As the wedge-shaped annular metal object 11, a closed annular metal object may be used, or an annular metal object that is divided into a plurality of parts in the circumferential direction may be used.

  In the embodiment of FIGS. 6 and 7, since the conical outer steel pipes 3 and 3A are joined to the pile 1A directly or via the annular hardware 11, when a bending moment acts on the pile 1A, Direct load transmission from the pile 1A to the conical outer steel pipes 3 and 3A increases, and direct load transmission from the entire circumferential surface of the pile 1A including the tension side to the conical outer steel pipes 3 and 3A is performed. Therefore, it is possible to more effectively utilize the excellent structural characteristics of the conical outer steel pipes 3 and 3A that utilize the component force in the axial direction of the hypotenuse.

  Moreover, in the embodiment of FIGS. 6 and 7, the fixing bar 6 is not installed at the upper end portion of the pile 1 </ b> A, but the conical outer steel pipe 3, 3 </ b> A is directly or via the annular hardware 11. Therefore, it is possible to transmit the axial pushing force and pulling force between the pile 1A and the conical outer steel pipes 3 and 3A. Further, the force is transmitted to the footing 2 through the fixing bars 5. Is also possible.

  Further, in the embodiment of FIG. 7, since the wedge-shaped annular metal piece 11 is used as the annular metal object interposed between the conical outer steel pipe 3A and the pile 1A, the dimensional error is absorbed and the conical outer It can be fitted between the end of the small diameter side of the steel pipe 3A and the pile 1A without a gap. Moreover, in the case of joining by welding, downward welding is possible and workability is good.

FIG. 8: is a longitudinal cross-sectional view which shows the joining structure of the pile head which concerns on the 4th Embodiment of this invention.
In the present embodiment, an annular mounting plate 13 is fixed to the outer surface of the pile 1A by welding or the like in advance before placing the pile 1A. A conical outer steel pipe 3A is placed around the head of the pile 1A with the large-diameter side facing upward, and is placed on the placing plate 13 of the pile 1A. The upper end of the conical outer steel pipe 3A substantially coincides with the upper end of the pile 1A. Between the lower end portion of the conical outer steel pipe 3A and the pile 1A, an annular hardware (metal) 14 having a trapezoidal cross-sectional shape and a circular inner surface is fitted from the upper side. 1A is joined by welding or the like. In the case of joining by welding, welding is performed downward from the upper side. As the wedge-shaped ring-shaped metal piece 14, a closed ring-shaped metal piece may be used, or a ring-shaped metal piece divided into a plurality of pieces in the circumferential direction may be used.

In the present embodiment, the pushing force in the vertical direction can be transmitted from the pile 1A to the conical outer steel pipe 3A and further to the footing 2 via the mounting plate 13, and the pulling force is a wedge-shaped annular metal fitting. The wedge effect of 14 can be transmitted from the pile 1A to the conical outer steel pipe 3A and further to the footing 2.
Moreover, since the wedge-shaped annular metal piece 14 is used as the annular metallic object interposed between the conical outer steel pipe 3A and the pile 1A, the end portion on the small diameter side of the conical outer steel pipe 3A and the pile are absorbed. 1A can be fitted without a gap. In addition, when the annular metal piece 14 is joined to the pile 1A by welding, the workability is good because only one point between the wedge-shaped annular metal piece 14 and the pile 1A is welded downward.

FIG. 9: is a longitudinal cross-sectional view which shows the joining structure of the pile head which concerns on the 5th Embodiment of this invention.
In the present embodiment, an annular bearing plate 15 is fixed to the upper end of the pile 1 so as to protrude inward and outward of the pile 1. A fixing member 16 such as a plate nut is attached to the upper end of the fixing bar 5.

  In this embodiment, since the bearing plate 15 is fixed to the upper end of the pile 1, it is possible to transmit the axial force of pushing and pulling between the pile 1 and the footing 2. That is, when a pulling force acts on the pile 1, the pulling force is transmitted from the bearing plate 15 to the concrete of the footing 2 and the solidified material 4. Further, the pulling force can be transmitted from the solidified material 4 to the footing 2 via the conical outer steel pipe 3 and the fixing bar 5, and the conical outer steel pipe 3 is used in combination with the bearing plate 15 and the conical outer steel pipe 3. Even if the protrusions and the like are not provided on the inner surface of 3, the structure stable against the pulling force can be obtained.

Further, the bearing plate 15 increases the fixing degree of the head of the pile 1 when a bending moment acts on the pile 1, and also has an effect of increasing the bending moment that can be borne by the pile 1 without being transmitted to the conical outer steel pipe 3. I can expect. At this time, axial support pressure is transmitted from the bearing plate 15 to the solidified material 4 on the tension side of the pile 1, but a restraining effect on the solidified material 4 is exerted between the pile and the conical outer steel pipe 3. The bending strength of the one-head joint can be further increased.
The bearing plate 15 has an area and rigidity capable of distributing and transmitting a load when an axial pushing force, a pulling force, or a bending moment is applied and preventing the bearing failure of the concrete of the footing 2 and the solidified material 4. Anything is acceptable.

  In the present embodiment, since the fixing member 16 is provided at the end of the fixing stripe 5, the fixing length of the fixing stripe 5 in the footing 2 can be shortened. Thereby, the reinforcement in the footing 2 can be facilitated, the workability can be improved, or an increase in the fixing length when a high-strength reinforcing bar is used can be suppressed.

FIG. 10: is a longitudinal cross-sectional view which shows the joining structure of the pile head which concerns on the 6th Embodiment of this invention.
In the present embodiment, the conical outer steel pipe 3B is formed in a shape in which a cylindrical portion 3b having a cylindrical shape is formed at the end on the large diameter side of the conical outer steel pipe 3 in FIG. The fixing bar 5 is fixed to the inside of the cylindrical portion 3b by welding. A fixing member 16 is attached to the upper end of the fixing muscle 5. A substantially upper half of the cylindrical portion 3 b is embedded in the footing 2.
Moreover, the cyclic | annular protrusion 17 (three in this example) is provided in the up-down direction at the outer surface which faces the solidification material of the pile 1 at intervals. A plurality (three in this example) of annular projections 18 are provided on the inner surface of the conical outer steel pipe 3B at intervals in the vertical direction.

In the present embodiment, since the cylindrical portion 3b is formed at the upper end portion of the conical outer steel pipe 3B, the fixing muscle 5 can be easily fixed, and the bent portion of the fixing muscle 5 can be eliminated. In addition, since the portion embedded in the footing 2 becomes a vertical surface, the structure of this portion becomes a more stable and reliable structure.
In addition, since the fixing bar 5 is fixed to the inner surface of the conical outer steel pipe 3B, the entire length of the fixing bar 5 is embedded in a solidified material such as concrete, and corrosion can be prevented.
In this embodiment, the fixing bar 5 is directly fixed to the conical outer steel pipe 3B by welding, but instead of this, for example, a coupler (screw) fixed to the conical outer steel pipe 3B by welding or the like in advance. It is also possible to eliminate the welding work in the field by fixing the fixing bar 5 using a connecting tool with a hole.

Moreover, in this Embodiment, while the protrusion 17 is provided in the outer surface which faces the solidification material of the pile 1, and the protrusion 18 is provided in the inner surface of the conical outer steel pipe 3B, the conical outer The steel pipe 3B, the solidified material 4, and the pile 1 are prevented from shifting from each other, and a rigid cross section is formed. Thereby, the cross-sectional performance when a bending moment acts on the pile 1 can be greatly improved, and a more stable structure can be constructed against the axial force of pushing and pulling.
As a method of forming the protrusion, it can be easily constructed by welding a steel plate or a reinforcing bar to a pile or a conical outer steel pipe and integrating them.

It is a longitudinal cross-sectional view which shows the joining structure of the pile head which concerns on the 1st Embodiment of this invention. It is a perspective view for demonstrating the mounting method to the pile of a conical outer steel pipe equally. It is a conceptual diagram which shows transmission of force when a bending moment acts on the joining structure of the pile head part of FIG. It is a longitudinal cross-sectional view for demonstrating the area | region of the ground which needs excavation about the junction structure of the pile head of FIG. It is a longitudinal cross-sectional view for demonstrating the area | region of the ground which needs excavation about the junction structure of a pile head as a prior art example. It is a longitudinal cross-sectional view which shows the joining structure of the pile head which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the joining structure of the pile head which concerns on the 3rd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the joining structure of the pile head which concerns on the 4th Embodiment of this invention. It is a longitudinal cross-sectional view which shows the joint structure of the pile head which concerns on the 5th Embodiment of this invention. It is a longitudinal cross-sectional view which shows the joint structure of the pile head which concerns on the 6th Embodiment of this invention. It is a conceptual diagram which shows the joining structure of the conventional pile head. It is a longitudinal cross-sectional view which shows the other example of the joining structure of the conventional pile head. It is a longitudinal cross-sectional view which shows the further another example of the joining structure of the conventional pile head.

Explanation of symbols

1, 1A Pile 2 Footing (concrete structure)
3, 3A, 3B Outer steel pipe 3b Cylindrical part 4 Solidified material 5 Anchorage 6 Anchorage 11, 14 Ring metal (metal)
13 Mounting Plate 15 Supporting Plate 16 Fixing Member 17, 18 Projection

Claims (9)

  A conical outer steel pipe with anchoring bars fixed on the large diameter side is arranged around the head of the pile installed in the ground with the large diameter side facing up, and in the gap between the outer steel pipe and the pile. A pile head joint structure characterized by being filled with a solidifying material and having at least a large-diameter end of the conical outer steel pipe embedded in an upper concrete structure.   The joint structure of the pile head according to claim 1, wherein a hardware is arranged between the outer steel pipe and the pile.   The pile head joint structure according to claim 1 or 2, wherein the outer steel pipe is placed on a placement plate fixed to an outer surface of the pile.   The pile head joint structure according to any one of claims 1 to 3, wherein each or any one of the pile, the outer steel pipe, the hardware, and the mounting plate is joined.   The pile head joint structure according to any one of claims 1 to 4, wherein a cylindrical portion is formed at an upper end portion of the outer steel pipe, and the fixing bars are fixed to the cylindrical portion.   The pile head joint structure according to any one of claims 1 to 5, wherein a bearing plate is fixed to an upper end portion of the pile.   The pile head according to any one of claims 1 to 6, wherein a fixing bar embedded in the concrete structure is fixed to an upper end portion of the pile and / or the bearing plate. Junction structure.   A fixing member is fixed to at least one upper end portion of the fixing bar provided in the outer steel pipe, the fixing bar provided in the pile, and the fixing bar provided in the bearing plate. The pile head joint structure according to any one of claims 1 to 7.   9. The pile head joint structure according to claim 1, wherein protrusions are provided on an outer surface of the pile facing the solidified material and / or an inner surface of the outer steel pipe.

Images